Sedimentary and Metamorphic Petrology Review

Lacustrine

Sediments associated with lakes and standing water.

Channel Geometry

Shape and structure of river channels.

Meandering

Single channel with high sinuosity and low gradient.

Point Bars

Finer sand deposits on inner river bends.

Cutbanks

Eroded banks on outside of river bends.

Saltation

Bouncing movement of sediment grains.

Creep

Large particles rolled along the surface.

Abrasion

Rock surface shaping by wind-driven sandblasting.

Deflation

Erosion of loose particles by wind.

Star Dunes

Dunes with variable arms and wind directions.

Loess

unconsolidated, unstratified aggregation of small angular mineral fragments, usually buff in color

Deflation Lag Deposits

Coarse clasts remaining after finer particles are removed.

Sediment Load

Amount of sediment transported by a river.

Ice Shelves

Floating ice sheets attached to land.

Till

Nonsorted glacial drift from melting ice.

Glacial Striations

long parallel scratches and grooves tgat are produced by rocks embedded in the ice scraping against the rock underlying the glacier

Moraines

Linear deposits of till from glaciers.

Dropstone

Large rock deposited on seafloor by glaciers.

Glacial Valleys

U-shaped valleys eroded by glacial ice.

Aretes

Sharp ridges between glacial valleys.

Delta

Depositional body where river meets sea.

Buoyancy

Ability of water to support sediment particles.

Alongshore winds

Winds parallel to the shore affecting sediment movement.

Tide-dominated delta

Delta with linear features parallel to tidal flow.

Wave-dominated delta

Delta shaped by wave action into smooth arcs.

Barrier reefs

Reefs separated from shore by a lagoon.

Atoll

Ring-shaped coral reef surrounding a lagoon.

Continental shelf

Shallow seabed extending from the shore.

Continental slope

between the continental shelf and continental rise

Continental rise

Between continental and abyssal plain.

Turbidites

Deposited by sediment-laden underwater currents.

Metamorphism

Transformation of rocks without melting.

Protoliths

Original rocks that undergo metamorphic changes.

Metamorphic Texture

minerals have grown in situ and interlocking

Metamorphic Minerals

Distinct minerals that only grow under metamorphic conditions.

Metamorphic Foliation

defined by parallel alignment of platy minerals

Differential Stress

Unequal forces applied to rocks, affecting their structure.

Isochemical Metamorphism

Metamorphism with minimal chemical change, except volatiles.

Metasomatism

Chemical exchange during open system metamorphism.

Mineral Assemblages

Specific combinations of minerals formed during metamorphism.

Erosional Features

Landforms created by the removal of rock material.

Metamorphic Facies

Domain defined by specific mineral assemblages.

Pressure-Temperature Space

Range of conditions affecting metamorphic processes.

Contact Metamorphism

High temperature, low pressure

Burial

Continued diagenesis

T-P Ranges

100-800°C and 1-10 kb pressure.

Lineation

any linear fabric elements

Gneissose Structure

- either a poorly-developed schistosity or segregated into layers by metamorphic processes
- these rocks are generally coarse grained.

Slate

compact, very fine grained metamorphic rock with a well developed cleavage

Phyllite

A rock with a schistosity in which very fine phyllosilicates, although rarely coarse enough to see unaided, impart a silky sheen to the foliation surface

Skarn

a contact metamorphosed and silica metasomatized carbonate rock containing calc-silicate minerals, such as grossular, epidote, tremolite, vesuvianite, etc.

Mineral Assemblages

Specific minerals characterizing metamorphic facies.

Metamorphic Rock Classification

Based on texture and mineral composition.

Granulite

High-grade rock with OH-free minerals.

Muscovite

Absent in granulite, a common mica.

Plagioclase

Common mineral in granulite and amphibolite.

Greenschist

Low-grade metamorphic rock, foliated with green minerals.

Greenstone

Non-foliated equivalent of greenschist.

Chlorite

Green mineral found in greenschist and gneiss.

Epidote

Green mineral often present in greenschist.

Amphibolite

Metamorphic rock dominated by hornblende and plagioclase.

Hornblende

Common amphibole mineral in amphibolite.

Eclogite

Green and red rock with clinopyroxene and garnet.

Clinopyroxene

Key mineral in eclogite, often omphacite.

Garnet

Common mineral in eclogite, includes pyrope.

Migmatite

Composite rock with dark gneissic and light felsic parts.

Non-foliated Rocks

Simpler metamorphic rocks without layered structure.

Weathering

The chemical alteration, physical, and biological breakdown of rock during exposure to the atmosphere, hydrosphere, and biosphere

Deposits

Accumulations of sedimentary materials in layers.

Erosion

Removal of sediment from its original location.

Bedload Movement

Movement of particles along the bottom of a stream.

Sedimentary Facies

Distinct sedimentary rock mass with unique characteristics.

Competence

Maximum particle size a stream can carry.

Alluvial Fan

Fan-shaped sediment deposit from mountain runoff.

Thalweg

Deepest point in a channel cross section.

Eolian

Wind-related processes of sediment deposition.

Suspension

Fine particles lifted into the air by wind.

Wind Erosion

Erosion caused by wind's mechanical and chemical action.

Braided River

Multiple channels with low sinuosity and high slope.

Transverse Dunes

large fields of dunes that resemble sand with a steep face in the downwind side

Linear Dunes

Long straight dunes formed by converging wind directions.

Parabolic Dunes

U-shaped dunes with open ends facing upwind.

Glacial Environment

Landforms and processes associated with glaciers.

Glacier

Permanent ice body moving due to gravity.

Snowline

Elevation where snow persists year-round.

Alpine Glacier

Small glaciers in mountainous regions.

Ice Sheets

Largest glaciers covering extensive land areas.

Barchans Dunes

Crescent-shaped dunes formed by wind.

Plucking

Particle detachment by moving glacial ice.

Abrasion

Grinding of bedrock by glacial debris.

Glacial Drift

General term for glacial deposits.

Tillite

Rock formed from consolidated till.

Cirques

Bowl-shaped depressions at glacier heads.

Horns

Sharp peaks from multiple cirques.

Water yield

Volume of water flowing in a river.

Water density differences

Variations in density between river and sea water.

Shelf slope

Incline of the continental shelf impacting delta shape.

Wave energy

Energy from waves affecting sediment distribution.

Tidal energy

Energy from tides influencing coastal sedimentation.

Tectonics

Geological processes affecting basin subsidence.